This quote is featured on the author Susan Wise Bauer's website. Bauer is writing a several volume history of the world, that has been getting good reviews. She also has written a book called The Well-Educated Mind: A Guide to the Classical Education That You Never Had, which looks really interesting as well.
I love Tuchman, and this quote articulates the reason why. Reading her Guns of August changed my opinion of reading history books altogether.